The selection of the site of a dock is generally confined within narrow limits such as railway connection, roads, location of the want of dock accommodation, currents, the proper position of the entrances, &c., &c.; nevertheless the nature of the soil should be considered, for upon a tidal river a few hundred feet one way or other may cause the works to be upon various kinds of earth each more or less treacherous, and when intermixed perhaps more unstable. Even upon one side of a comparatively narrow river the earth may be in a much more stable condition than upon the other; and when an old watercourse or a dry ditch passes across the site of a dock it must not be disregarded, as failures and damage have occurred because the same section of a wall was continued throughout. It is then necessary to adopt a system of construction suitable for softer or less stable ground, and especially so if the wall has to be built upon a firm stratum overlying sand, as a diminution in the thickness of the bed may cause a settlement and the wall to be pushed forward; for there is always danger in sandy soils, unless the superimposed layer is of considerable thickness, that the latter may be pierced and the whole site be in jeopardy from a flow of the sand. It may be that a dock must be built at a particular place, although the ground may be full of springs, the beds inclined, or a level stratum overlies an inclined bed of rock or softer earth incapable of standing at any but a flat slope, the whole being an unstable mass, for the deposits may extend to such considerable depths that to go below them is impracticable; however, uniform weighting and consolidation by the deposition of firm soils having insoluble particles will generally make it firmer, and by compression and admixture will ultimately cause the ground to be more solid. It should be loaded as long as possible, and the material be deposited beyond the site so as to prevent the outside and less consolidated earth slipping upon the works, and as it will be disturbed by the loaded portion having subsided it may require slight support upon the lower portion of the slope. When the settlement over the base and the slopes to the original bed is equal and regular and care is taken that the soft soil cannot run, by a due protection of its surface it can be built upon. The rise of the mud in front and for some distance from the wall is generally from about one-third to one-half of its subsidence when loaded. The rate of sinking and uplifting of the soil should be noticed, and whether it is equable and the depth to which settlement extends is the same over a considerable area and practically ceases at a certain depth.